Method of frabricating a plural finned heat exchanger

ABSTRACT

A tubular heat exchanger having spine-type fins formed integrally from the wall thereof and disposed therearound, with the fins cut from ribs extending longitudinally of the heat exchanger, and a method of manufacture which includes rotary movement between a tool and an elongated, ribbed tubular member relative to the longitudinal axis of the latter.

[Jnited States Patent 1191 Pasternak [45] *Feb. l2, 1974 [541 METHOD OFFRABRICATING A PLURAL [56] References Cited FINNED HEAT EXCHANGER UNITEDSTATES PATENTS [75] Inventor: Stephen F- Pasternak, Park Ridge,3,202,212 s/1965 Kmzer 29/1573 A 111. 3,360,040 12/1967 Kritzer...29/157.3 A X 3 659,326 5 1972 K 'th 29 157.3 A [73] Assignee: Peerless fAmerica Incorporated 2,327 757 851943 B1-ren 2951573 A Chicago, 111.

[ Notice: The portion of the term of this Primary Examiner-Charles W.Lanham patent subsequent to Apr. 17, 1990, Assistant Examiner-D. C.Reiley, III has been disciaimed. Attorney, Agent, 0r Firm-Root & OKeeffe[22] Filed: Aug. 7, 1972 [21] Appl. No.: 278,401 [57] ABSTRACT A tubularheat exchanger having spine-type tins Related US Appllcat'on Data formedintegrally from the wall thereof and disposed [621 Division 0f Ser- NO-13,297, Feb- 24, 1970, Pat. NO- therearound, with the ns cut from ribsextending lon- 37271682 gitudinally of the heat exchanger, and a methodof manufacture which includes rotary movement be- [52] Us' CL 29/157-3 B29/157-3 A 72/71 tween a tool and an elongated, ribbed tubular member [5Intrelative to the longitudinal axis of the latter. [58] Field of Search29/l57.3 A, 157.3 B; 72/71 9 Claims, 14 Drawing Figures Patented Feb.12, 1974 3,791,003

4 Sheets-Sheet l Patented Feb. l2, 1974 3,791,003

4 Sheets-Sheet 2 Patented Feb. 12, lQ'M i 3,791,0@3

4 Sheets-Sheet 5 Patented Feb l2, 1974 3,791,03

4 Sheets-Sheet 4 METHOD F FRABRICATING A PLURAL FINNED HEAT EXCHANGERThisis a division of U.S. Pat. application Ser. No. 13,297, filed Feb.24, 1970, now vU.S. Pat. No. 3,727,682.

BACKGROUND OF THEINVENTION This invention relates to heat exchangers andthe method of .making the same.

. lt is a primary object of the present invention to afford a novel heatexchanger.

It is another object of the present invention to afford a novel methodof making heat exchangers.

Another object is to enable a novel heat exchanger of the type embodyingintegrally formed spine-type fins to be afforded in a novel andexpeditious manner.

Heretofore, the integral spine-fin type of heat exchangers used in theheat exchanger fields commonly have been of three types, namely, heatexchangers embodying needle-like spines, such as, for example, thosedisclosed in R. W. Kritzer United States Letters Patent No. 2,247,243;heat exchangers embodying spines cut or gouged out from one side, orfrom opposite sides, of a heat exchanger body, such as, for example,those disclosed in R. W. Kritzer United Sates Letter Patent No.3,202,212; and heat exchangers formed by transversely slittinglongitudinally extending fins, such as, for example, those shown in R.W. Kritzer United States Letters Patent No. 3,360,040.

Although spine-type heat exchangers of the aforementioned typesheretofore known in the art have been highly successful and have hadmuch commercial success, they have certain inherent disadvantages. Forexample, in the manufacture of heat exchangers of the type shown in theaforementioned Kritzer U.S. Pat. No. 2,247,243l the needle-like spinesare cut or gouged from the tubular wall of the heat exchanger inlrelative thin, sharp slivers, with rotary cutters, traveling on aplanetary path relative to the tubular member being commonly used forthis purpose. The speed of production commonly realized in forming suchheat exchangers has been relatively slow, being in the nature of one ortwo linear feetof tubing per minute.

Similarly, in the production of heat exchangers of the type shown in theaforementioned Kritzer U.S. Pat. No. 3,202,212 spines are gouged fromribs on one face or opposite faces of tubular members which arepreferably rectangular in shape. A'method commonly used for producingsuch spines has been to use reciprocating cutters, which reciprocatedlongitudinally ofthe heat exchanger. Such a method of production, ofcourse, has several disadvantages, such as, for example, that no work isperformed on the return stroke of such cutters. The speed of productionfor such heat exchangers also has been relatively slow, commonly beingin the naturel of two to four linear feet of tubing per minute.

Also,'although the production of heat exchangers of the type shown inthe aforementioned Kritzer U.S.-Pat. No. 3,360,040, wherein spines areformed by transversely slitting elongatedfins, may, under properconditions, be relatively high, such types of heat exchangers havecertain inherent disadvantages, such as, for example, that they arelimited as tothe number of spines which may be formed around theperiphery of the tubular member, when such relatively good productionspeed is afforded, because of the necessity of affording spacetherearound for the spine-forming mechanisms to engage the separatefms.

It is an important object of the present invention to overcomedifculties heretofore known in the art, and to enable heat exchangershaving integral spine-type fins to be commercially produced in a noveland expeditious manner at a production speed substantially higher thanthe speeds heretofore known in the art.

An object ancillary to the foregoing is to enable heat exchangers havingintegral spine-type tins to be commercially produced at productionspeeds several times greater than commercial production speedsheretofore known in the art.

Heat exchangers of the type embodying spine-type fins projectingoutwardly from a tubular member and disposed therearound have beenheretofore known in the art in the form of heat exchangers wherein thefins are formed separately from the tubular member in ribbon-like form,and the ribbons are then wrapped around the body portion and attachedthereto. This, of course, has the inherent disadvantage of requiring aplurality of separate operations, and affording a fin structure whichmust be attached or bonded to the tubular member, with the attendantdanger of poor heat transfer between the fins and tubular member. It isanother object of the present invention to overcome such disadvantages.

Another object of the present invention is to enable a novel heatexchanger to be afforded, which is of the type which embodies spine-typetins projecting outwardly from and disposed completely around the bodyportion thereof, and wherein the fins are formed integral with the bodyportion as distinguished from fins formed separately and then attachedto a body portion.

Another object of the present invention is to afford a novel heatexchanger embodying a tubular body portion having elongated ribsextending longitudinally thereof and spaced therearound, with spine-typefins projecting outwardly from the ribs.

An object ancillary to the foregoing is to enable such ribs to beclosely spaced around the body portion.

Another object is to enable spine-type fins to be formed in a novel andexpeditious manner from ribs extending longitudinally of a tubular bodymember.

Yet another object is to afford a novel method of producing a heatexchanger having .a tubular body portion with spine-type finsprojectingtherefrom, wherein a cutting tool and a tubular member arerotated relative to each other in such a manner that the tool passesaround the peripheral surface of the tubular member in a mannereffective to cut the fins from the peripheral surface and to raise theminto outwardly projecting position.

A further object is to afford'a novel method of the aforementioned typewherein such tins are cut and raised in the aforementioned manner fromlaterally spaced, longitudinally extending outwardly projecting ribs onthe periphery of such a tubular member.

Another object is to enable such fins to be so cut and raised from ribsin a novel and expeditious manner whereby the same cutting toolsimultaneously cuts and raises fins on a plurality of adjacent ribs.

A further object of the present invention is to afford a novel heatexchanger having spine-type fins project ing therefrom and spaced aroundand longitudinally of the tubular body portion thereof, and wherein theshape and configuration of the fins may be controlled in a novel andexpeditious manner.

Another object is to enable a novel heat exchanger having spine-typefins cut from the material on the outer periphery of a tubular bodymember, and

wherein the length of the fins is substantially the same as the lengthof the cut made in the body member.

Another object of the present invention is to afford a novel heatexchanger of the aforementioned type, which is practical and efficientin operation and which may be readily and economically producedcommercially.

Other and further objects of the present invention will be apparent fromthe following description and claims and are illustrated in theaccompanying drawings which, by way of illustration, show preferredembodiments of the present invention and the principles thereof and whatI now consider to be the best mode in which I have contemplated applyingthese principles. Other embodiments of the invention embodying the sameor equivalent principles may be used and structural changes may be madeas desired by those skilled in the art without departing from thepresent invention and the purview of the appended claims.

DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. l is a somewhat diagrammatic, perspective view illustrating oneembodiment of the present invention and apparatus suitable for carryingout certain steps employed in the practice of the method of the presentinvention;

FIG. 2 is a fragmentary, detail sectional view taken substantially alongthe line 2-2 in FIG. 1;

FIG. 3 is a fragmentary perspective view of a heat exchanger embodyingthe principles of the present invention;

FIG. 4 is an enlarged, detail sectional view taken substantially alongthe line 4-4 in FIG. 3;

FIG. 5 is an enlarged, fragmentary, detail elevational view of a portionof the heat exchanger shown in FIG. 4;

FIG. 6 is a fragmentary, elevational view looking in the direction ofthe arrow 6-6 in FIG. 5;

FIG. 7 is a fragmentary, side elevational view of a portion of the stockshown in FIG. l;

FIG. 8 is a fragmentary, top plan view looking substantially in thedirection of the arrows 8-8 in FIG. l; FIG. 9 is a bottom plan view ofthe tool shown in FIG. 8;

FIG. 10 is an end elevational view of the tool shown in FIG. 8;

FIG. l1 is a diagrammatic view illustrating the operation of the toolshown in FIG. 1 on the work piece shown therein;

FIG. l2 is a fragmentary perspective view, similar to FIG. 3, butshowing a modified form of the heat exchanger;

FIG. 13 is a perspective view similar to FIG. l, but illustrating otherapparatus suitable for carrying out steps employed in the practice ofthe method of the invention; and

FIG. 14 is a perspective view similar to FIGS. 1 and 13, butillustrating still other apparatus suitable for carof the invention.

DESCRIPTION OF THE EMBODIMENTS SHOWN HEREIN In FIG. 3 of the drawings isshown a presently preferred form of heat exchanger 1, embodying theprinciples ofthe present invention; and in FIG. 1 is illustratedapparatus 2 for carrying out certain steps employed in the practice ofthe method of the present invention.

In FIG. 1, ribbed tubular stock 3 is shown being fed through theapparatus 2 to afford a heat exchanger l of the form shown in FIG. 3.The tubular stock 3 embodies a wall 4 having a plurality of outwardlyprojecting, closely spaced, elongated ribs 5 on the periphery thereof,the ribs S extending parallel to the longitudinal axis of the tubularstock 3.

In the operation of the apparatus 2 shown in FIG. 1, the tubular stock 3is fed longitudinally in the direction of the arrow 6 through an opening7 in a holding member 8 by a feed member 9. The holding member 8 is astationary part of the apparatus 2, and the opening 7 is fluted, and iscomplementary in shape to the outer periphery of the ribbed stock 3,being of such size that the stock 3 fits therein with a relatively snug,but freely slidable fit. Thus, the holding member 8 is effective to holdthe stock 3 against rotation during the passage thereof through theapparatus 2.

The feed member 9 may be of any suitable type, but is shown in F IG. 1as a gear disposed around the tubular stock 3 and having internalthreads l0 bitingly engaged with the outer periphery of the ribs 5 onthe stock 3. The gear 9 is suitably journaled in the apparatus 2 and isoperatively meshed with a gear l1 mounted on a drive shaft 12. Rotationof the drive shaft 12 in a counterclockwise direction, as viewed in FIG.1, is effective to drive the gear 11 in a counterclockwise direction andthereby drive the feed member 9 in a clockwise direction. Such rotationof the feed member 9, through the engagement of the threads 10 with theouter periphery of the tubular stock 3, is effective to advance thetubular stock 3 through the holding member 8 in the direction of thearrow 6.

Another gear 13, having an opening 14 therethrough, is suitablyjournaled in the apparatus 2 on the opposite side of the gear 13 fromthe feed member 9, and with the opening 14 in axial alignment with theopening 7 in the holding member 8, FIG. 1. The opening 14 issubstantially larger in diameter than the outside diameter of thetubular stock 3, and during operation of the apparatus 2, the stock 3,which is fed through the holding member 8 by the feed member 9, isadvanced through the opening 14 in the gear 13. A tool 15 is adjustablymounted on the face of the gear 13 remote from the holding member 8 bysuitable means such as bolts 16 extending through slots 17 in the gear13, FIGS. 1 and 2. The gear 13 is operatively meshed with a gear 18mounted on the drive shaft l2, and the aforementioned counterclockwiserotation of the drive shaft 12 is effective to similarly drive the gear18, and thereby rotate the gear 13 in a clockwise direction, as viewedin FIG. l. Such rotation of the gear 13 around the tubular stock 3 iseffective to move the tool 15 around the periphery of the stock 3 in acutting and forming operation effective to cut and raise spin-type fins19 on the tubular stock 3 as the latter moves away from the gear 13, aswill be discussed in greater detail presently.

The tool 15, preferably, is of a type which embodies an elongatedcutting edge 20, as illustrated in FIGS.

8-11, which cutting edge 20, when the tool 15 is properly disposed inoperative position relative to the tubular stock 3 during operation ofthe apparatus 2, is operatively engaged with a plurality of the ribs 5,FIGS. 8 and 11, so that spines 19 are being simultaneously formed onthese ribs. Thus, as diagrammatically illustrated in FIG. 11, as theleading end 21 of the cutting edge 20, during rotation of the tool in aclockwise direction around the tubular stock 3, operatively engages arib, such as the rib Sa, and begins to form a spine `19 thereon, theother portions of the tool l5 disposed between the leading end 21 andthe trailing end 22 of the cutting edge 20 are in progressively furtheradvanced engagement with ribs such as the ribs 5b, 5c, 5d and 5edisposed in a counterclockwise direction to the rib 5a, as viewed inFIG. 11. v

During operation of the apparatus 2, the tool 15 is so disposed relativeto the tubular stock 3, that during such rotation of the tool l5. aroundthe stock 3, as the leading end 21 of the cutting edge 20 moves intoengagement with one of the ribs 5, and then the cutting edge moves in alongitudinal direction, transversely across the thus engaged rib, to apoint wherein the trailing edge 22 moves away from that particular rib,the cutting edge 20 slices downwardly through the rib 5 along adownwardly and forwardly projecting path relative to the length of thetubular stock 3, as illustrated by the broken line 23 in FIG. 1. Suchmovement of the tool 1,5 relative to the rib 5 is effective to slice aportion of the rib 5, such as that represented by the reference numeral19a in FIG. 7, from the rib 5, the slicing by the tool 15 preferablyterminating at its lower end in upwardly spaced relation to the bottom24 of the rib 5, as illustrated in FIG. 7. During such operation of thetool l5, the lower farce 25 of the cutter portion thereof, FIG. 9, ridesdownwardly along the rib 5 on the side of the tool remote from theportion 19a being sliced therefrom, and the upper face 26 of the cutterportion, FIG. 8, rides along the lower face of the portion 19a, inengagement therewith, and is effective to raise the portion 19a intooutwardly projecting position to thereby afford an outwardly projectingspine, such as the spines 19 shown in FIG. 7 on the wall portion 4 ofthe tubular stock 3.

Thus, it will be seen that the spines 19 are cut from the ribs 5 in theapparatus 2 with a slicing action, as distinguished from the gougingaction, as occurs when a cut is made with a cutter that reciprocatesalong the path of cut, such as, for example, in a planing type ofaction.

One of the difficulties in forming spines on heat exchangers, such as,for example, the spines on heat exchangers of the form shown in theaforementioned Kritzer U.S. Pat. No. 3,202,212, by gouging the spinesfrom the underlying body portion of the heat exchanger, has been that itis difficult to control the thickness and length of spine for variousdepts of cut, because of the tendency of such operations to compact thespines, longitudinally, during such formation thereof. Because of thiscompacting action in so gouging spines, it commonly has been necessaryto afford a length of cut in such operations that was as much as twicethe length of the finished spine.

One of the advantages of forming spines on heat exchangers in accordancewith the preferred practice of the method of the present invention isthat it may be accomplished with relatively little, if any, suchcompacting. With the spines 19 formed by a tool such as the tool 15, inthe previously described manner, theindividual spines 19 are severed orcut from the respective ribs 5 with a slicing action, wherein thecutting edge moves longitudinally through the material being cut, andthus severed portion of the rib is then turned upwardly so that verylittle force, in a compacting direction, is applied to the spine duringthe formation thereof. Such a methodA of operation even enables spinesto be formed which are of relatively small thickness, such as, forexample, ten-thousandths of an inch, with the spines having an over-allfinished length which is little, if any, less than the length of cutused in forming the spines.

It will be remembered that another common disadvantage in methodsheretofore known in the art for producing heat exchangers havingspine-type tins thereon, has been the relatively low speed of productioninherent in the methods used and the types of heat exchangers formed,such speeds commonly being as little as less than a linear foot oftubing per minute and a maximum of 3 or 4 feet per minute. It isanticipated that in the manufacture of heat exchangers in accordancewith the principles of the present invention, production speeds of 25 to30 linear feet of tubing per minute, and more, may be realized.

In the preferred form of heat exchanger 1 shown in the drawings, FIGS.3-6, the spines 19 project outwardly from the wall portion or tubularbody member 4 in a relatively gently curving arc, transversely to thelength of the wall 4, throughout substantially the entire lengths of thespines 19. In the formation of the spines 19, the ribs 5 of the tubularstock 3 have been reduced to relatively small outwardly projectingremainders 27, FIGS. 4 and 5, throughout the entire length of the heatexchanger l disposed between the spines 19 at the opposite extremitiesthereof. The base portions 28 of the fins 19 are integral with therespective rib remainders 27 to afford good heat transfer connectionbetween the tins 19 and the wall portion 4 of the heat exchanger 1.

The ribs 5 on the tubular stock 3 are preferably rounded at theirradially outer extremities. With this construction, and with the spines19 formed in the aforementioned manner, the width of the spines 19,transversely to the length of the wall 4, tapers inwardly somewhatbetween the base 28 and the outer extremity 29 thereof, tending toterminate in a relatively narrow point at the outer extremity 29, FIG.5. With the spines 29 being formed-in the manner heretofore describedwith respect to the operation of v the apparatus 2, wherein the tool l5is rotated around the longitudinally advancing tubular stock 3, thespines 19 are sliced and formed from the ribs 5 along a helical path,with the pitch of the helix being equal to the longitudinal advanceofthe tubular stock 3 relative to the tool 15 during each revolution ofthe tool 15 around the tubular stock 3 and between each successiveoperative engagement of the tool 15 with each of the respective ribs 5.

Preferably, the shape of the cutting tool 15 is such that during theinitial engagement of the cutting edge 20 thereof with the outer face ofeach respective rib 5, the cut 23, FIG. 7, is formed at a shallow angle,such as two to three degrees, to the outer peripheral surface of therespective rib 5, with the cut thereafter progressing atan everincreasing angle to thereby afford a relatively smoothly arcuate cut.With' the tool l5 thus shaped, the thickness of the tins 19,longitudinally of the ribs 5, tapers from a narrow thickness at theouter extremities thereof to a greater thickness at the base portionsthereof. The increased width and increased thickness of the fins 19 fromthe outer extremities thereof to the bases thereof afford effective heattransfer paths for the transfer of heat between the wall portion 4 ofthe heat exchanger l and the surrounding working fluid, such as, forexample, air or liquid.

The tool l5, also is preferably so formed that the wiping action of thetop face 26 thereof against the lower face of the fm 19 being severedand raised from a respective rib 5 is such that during the raising ofthe fm 19 it is relatively smoothly curved substantially throughout itsentire length into an arcuate shape, FIG. 2. Also, the shape of the toolpreferably is such that the stresses exerted on the fins 19 as they aresevered and raised from the respective ribs 5 is such that they aretwisted axially through a partial turn between the bases and the outerextremities thereof, with the outer extremities being displaced aroundtheir axes from the bases at an angle of 10 to 30. With suchconstruction of the heat exchanger 1, a relatively small overall outsidediameter is afforded with relatively long fm lengths. Also, the fins areso disposed that they tend to effect turbulence in the air or otherfluid passing therebetween longitudinally of the wall 4, as well asturbulence in the air or fluid passing therebetween transversely to thelength of the wall 4.

The fins 19 of the heat exchanger l, shown in FIG. 3, are spaced alongeach of the ribs 5, with the ribs 5 being disposed in substantiallyparallel relation to the longitudinal axis of the wall 4. In addition,in the heat exchanger 1, adjacent fins 19 on adjacent ones of the ribs 5are spaced from each other in rows extending along a helical pathextending around the wall 4, with the adjacent ones of the rows oftransversely spaced fins 19 being disposed on respective turns of theaforementioned helical path.

As will be appreciated by those skilled in the art, although the form ofheat exchanger 1 shown in FIG. 3 illustrates the presently preferredform of heat exchanger embodying the present invention, it is shown onlyby way of illustration and not by way of limitation and other forms ofheat exchangers may be afforded, such as, for example, heat exchangerswherein the fins are disposed on two or more helical paths, or aredisposed on spaced rows extending around the wall 4 in substantiallyperpendicular relation to the longitudinal axis thereof, withoutdeparting from the broader aspects of the present invention.

In FIG. 12 a modified form of heat exchanger 1b is shown. The hatexchanger 1b is similar in many respects to the heat exchanger l shownin FIG. 3, and parts which are identical to parts shown in FIG. 3 areindicated by the same reference numerals and parts which are similar,but have been substituted for corresponding parts are indicated by thesame reference numerals with the suffix b" added.

The heat exchanger 1b is identical in construction to the heat exchangeI except that the rows 30h of fins 19, which extend longitudinally ofthe wall 4 are helically disposed relative to the longitudinal axis ofthe wall 4 of the heat exchanger 1b rather than being disposed insubstantially parallel relation thereto, as in the heat exchanger l.Such construction may be afforded in any suitable manner, such as, forexample, by extruding the longitudinal ribs on the tubular stock fromwhich the heat exchanger 1b is formed in the aforementioned helicalpaths. I-Iowever, preferably, the tubular stock is extruded with theribs 5 thereon disposed in parallel relation to the longitudinal axis ofthe stock, in the same manner as the tubular stock 3 shown in FIG. 1,and the stock is subsequently twisted around its longitudinal axis toalord the helical curvature of the ribs. Such stock may be fed throughthe apparatus 2 in the same manner as the stock 3 shown in FIG. 1, tothereby afford the heat exchanger l'a shown in FIG. 12, the fluting inthe opening 7 of the holding member 8 merely being changed toaccommodate the helical shaped ribs on the tubular stock.

In FIG. 13 a modified form of apparatus 2c is shown, and parts thereofwhich are the sarne as parts shown in FIG. 1 are indicated by the samereference numerals. In the apparatus 2c, as in the apparatus 2, a driveshaft 12, rotating in a counterclockwise direction is effective througha gear 18 mounted thereon to rotate a gear 13 in a clockwise directionand thereby correspondingly rotate a tool 15 around tubular stock 3having longitudinally extending ribs 5 thereon. A feed member 9 isdriven by a gear 1l mounted on the drive shaft 12 to advance the tubularstock 3 through the gear 13 in the direction of the arrow 6, asindicated in FIG. 13. Thus, in all these respects, it will be seen thatthe apparatus 2c is the same as the apparatus 2.

However, in the apparatus 2c, the holding member 8 is omitted and a gear32 having an opening 7 therethrough is journaled in the apparatus 2c. Agear 33 mounted on the drive shaft 12 is operatively meshed with anidler gear 34, which is in mesh with the gear 32, to thereby rotate thegear 32 in a counterclockwise direction upon corresponding rotation ofthe drive shaft 12. Like the opening 7 in the holding member 8 of theapparatus 2, the opening 7 in the gear 32 is complementary in size andshape to the outer periphery of the tubular stock 3. The tubular stock 3in the apparatus 2c extends through the opening 7 in the gear 32,between the feed member 9 and the gear 13 so that during operation ofthe apparatus 2c, when the drive shaft 12 is causing the tool 15 torotate in a clockwise direction around the tubular stock 3, it is alsocausing the gear 32 to rotate in the opposite, or clockwise, directionand thus turn the tubular stock 3 around its longitudinal axis.

The tool l5 in the apparatus 2c, shown in FIG. 13, is effective to sliceand form the spines 19 on the tubular stock 3 mounted therein in thesame manner as the tool 15 is effective to operate in the apparatus 2,shown in FIG. 1. The primary difference between the apparatus 2c and theapparatus 2 is that during the operation of the apparatus 2c both thetubular stock 3 and the tool 15 are being physically rotated, with therotation being in opposite directions so that the tool 15 in theapparatus 2c may rotate at a slower speed than the tool 15 in theapparatus 2 while still affording the same speed of production as in theapparatus 2. On the other hand, if desired, it will be seen that thespeed of production may be increased by using the apparatus 2c anddriving the tool 15 thereof at the same speed of rotation as that of thetool 15 of the apparatus 2.

In FIG. 14 of the drawings is shown another form of apparatus 2d forcarrying out the method of the present invention. This apparatus, also,is similar to the apparatus 2 shown in FIG. 1, and parts which are thesame as parts of the apparatus 2 are indicated by the same referencenumerals.

The apparatus 2d embodies the same drive as the apparatus 2c, shown inFIG. 13, for the tubular stock 3. This drive includes the drive shaft 12and the gear 11 for driving the feed member 9, and the gears 33 and 34for driving the gear 32, so that, in the operation of the apparatus 2d,the tubular stock 3 is rotated in a counterclockwise direction, asviewed in FIG. 14, and is fed longitudinally in the direction of thearrow 6. However, unlike the apparatuses shown in FIGS. 1 and 13, thetool l in the apparatus 2d is adjustably, but stationarily mounted. Suchmounting of the tool may be accomplished in any suitable manner, but isshown in FIG. 14 as being effected by means of a clamp 32' mounted on acarriage 33', which may be stationarily positioned in the apparatus 2d.The tool l5 in the apparatus 2d is releasably secured in the clamp 32'by a bolt 34', and the clamp 32' is adjustable longitudinally of thecarriage 33', and may be secured thereto by any means well known in theart, such as, for example, a clamp 35 engageable in a longitudinal `slot36 in the carriage 33.

In the operation of the apparatus 2d, shown in FIG. 14, the rotation ofthe tubular stock 3 around its longitudinal axis is in acounterclockwise direction, so that the relative movement between thetool 15 and the stock 3 in the apparatus 2d is the same as that of theapparatus 2 shown in FIG. 1. Thus, during operation of the apparatus 2d,spines 19 are formed on the ribs 5 projecting radially outwardly fromthe wall 4 of the tubular stock 3 in the same manner as the fins 19 areformed in the operation of the apparatus 2, the only difference inoperation being that, in the apparatus 2, the tool 15 rotates and thetubular stock 3 does not, and, in the apparatus 2d, the reverse occurs,namely, the tubular stock rotates and the tool l5 does not.

It is to be observed that in FIGS. 1, 13 and 14 the first spines 19formed on the tubular stock 3 shown therein are shown as formed ininwardly spaced relation to the leading end of the stock 3 as it movesthrough the respective apparatuses. As will be appreciated by thoseskilled in the art, this is merely by way of illustration, and not byway of limitation, and the first spines 19 may be formed on the tubularstock in closely adjacent relationship to the leading end thereof, ifsuch construction is desired. However, with the spines 19 formed on thetubular stock 3in the manner shown in FIGS. 1, 13 and 14, after thespine-forming operations have been completed on the tubular stock 3, theribs extending ahead of the first spines 19 may be removed from theperiphery of the wall 4, such as, by grinding, to afford an end portionhaving a smooth peripheral surface 37, as shown on the heat exchangers land 1b illustrated in FIGS. 3.and l2, respectively, to thus afford aconnecting nipple, or the like, at the end of the heat exchanger 1. Onthe other hand, if desired, the stock 3 may be cut off betweentheadjacent rows 31 of spines 19 or immediately adjacent the leading spines19, so as to afford a heat exchanger, not shown, wherein the spines 19are disposed immediately adjacent to the end of the wall 4. It will beunderstood, of course, that any one of these constructions may beafforded at either one or both ends of the completed heat exchangers 1and la.

From the foregoing it will be seen that the present invention affords anovel method for manufacturing heat exchangers of the integralspined-fin type. It is well adapted for use on various materials, suchas, for example, the softer metals, such as, for example, copper andaluminum tubing, as well as the harder metals, such as, for example,stainless steel tubing. i

Also, it will be seen that the present invention affords a novel methodof making heat exchangers of the spined-fin type, which is well adaptedfor high speeds of production.

In addition, it will be seen that the present invention affords a novelmethod of manufacturing heat exchangers of the aforementioned spined-fintypes at high production speeds, with the spines spaced from each otheraround the wall of the heat exchanger at substantially any desireddistance, and with the spacing being uniform or non-uniform, as desired.Also, if desired, this may be accomplished with only one cutting tool,the spacing of the longitudinally extending ribs on the tubular stockfrom which the heat exchanger is formed, determining the spacing of thespines around the wall of the heat exchanger.

Furthermore, it will be seen that the present invention affords a novelmethod for forming heat exchangers of the aforementioned type, which iswell adapted to handle tubular stock of substantially any practical,desired length. Thus, it will be seen that straight tubular stock ofvarious lengths may be fed through any of the apparatuses shown in FIGS.1, 13 and 14, and, if desired, tubular stock even could be fed from acoil, or the like, through apparatus of the type shown in FIG. l, in thepractice of the method of the present invention.

In addition, it will be seen that the method of the present inventionaffords a novel method of forming heat exchangers having spined-finsdisposed therearound, with the fins being of various selected or desiredshapes. This, of course, can be accomplished by the proper formation ofthe tool 15. However, equally, if not more importantly, this also can beaccomplished by varying the shapes of the ribs 5 on the tubular stock 3.

Furthermore, it will be noted that the present invention affords a novelheat exchanger of the aforementioned spined-fin type, wherein the finsare spaced longitudinally along ribs on the heat exchanger, and, inaddition, may be spaced, at substantially any desired spacing, aroundthe entire periphery of the heat exchanger.

Thus, it will be seen that the present invention affords a novel heatexchanger, which is practical and efficient in operation and which may be readily and economically produced commercially; and, in addition,affords a novel method of making heat exchangers.

Thus, while I have illustrated and described the preferred embodimentsof my invention, it is to be understood that this is capable ofvariation and modification, and I therefore do not wish to be limited tothe precise details set forth but desire to avail myself of such changesand alterations as fall within the purview of the following claims.

I claim:

1. The method of making finned heat exchanger tubing comprising a.providing an elongated tube having longitudinally extending externalribs thereon, and

b. using a cutting tool having a cutting edge and a face projectingtherefrom, rotating said cutting and said tube relative to each otheraround the longitudinal axis of said tube in such position as tosimultaneously cause l. said cutting edge to slice said ribs to affordrib portions cut from other rib portions, and 2. said face to bend saidfirst mentioned rib portions outwardly away from said other ribportions. 2. The method defined in claim 1, and in which a. said slicingand bending are simultaneously accomplished on a plurality of said ribs.3. The method defined in claim l, and in which a. said ribs aresubstantially parallel to the longitudinal axis of said tube. 4. Themethod defined in claim 1, and in which a. said ribs are curved aroundsaid tube in substantially helical form. 5. The method defined in claiml, and in which a. said tool is stationary during said relative rotationof said tool and tube. 6. The method defined in claim 1, and in which a.said tube is stationary during said relative rotation of said tool andtube.

7. The method defined in claim 1, and in which a. said tube rotatesaround its longitudinal axis during said relative rotation of said tooland tube b. said tool rotates around the periphery of said tube duringsaid relative rotation of said tool and tube.

8. The method defined in claim 1, and in which a. said tool, when inoperative engagement with one of said ribs for so slicing and bendingsaid one rib, is, at all times during said relative rotation of saidtool and tube, in position to so slicingly and bendingly engage the nextadjacent rib in the direction of travel of said tool relative to saidtube during said relative rotation of said tool and tube.

9. The method defined in claim 8, and in which a. said tool is inoperative simultaneous engagement with a plurality of said ribs wherebysaid slicing and raising are simultaneously accomplished on a pluralityof said ribs.

1. The method of making finned heat exchanger tubing comprising a.providing an elongated tube having longitudinally extending externalribs thereon, and b. using a cutting tool having a cutting edge and aface projecting therefrom, rotating said cutting and said tube relativeto each other around the longitudinal axis of said tube in such positionas to simultaneously cause
 1. said cutting edge to slice said ribs toafford rib portions cut from other rib portions, and
 2. said face tobend said first mentioned rib portions outwardly away from said otherrib portions.
 2. said face to bend said first mentioned rib portionsoutwardly away from said other rib portions.
 2. The method defined inclaim 1, and in which a. said slicing and bending are simultaneouslyaccomplished on a plurality of said ribs.
 3. The method defined in claim1, and in which a. said ribs are substantially parallel to thelongitudinal axis of said tube.
 4. The method defIned in claim 1, and inwhich a. said ribs are curved around said tube in substantially helicalform.
 5. The method defined in claim 1, and in which a. said tool isstationary during said relative rotation of said tool and tube.
 6. Themethod defined in claim 1, and in which a. said tube is stationaryduring said relative rotation of said tool and tube.
 7. The methoddefined in claim 1, and in which a. said tube rotates around itslongitudinal axis during said relative rotation of said tool and tube b.said tool rotates around the periphery of said tube during said relativerotation of said tool and tube.
 8. The method defined in claim 1, and inwhich a. said tool, when in operative engagement with one of said ribsfor so slicing and bending said one rib, is, at all times during saidrelative rotation of said tool and tube, in position to so slicingly andbendingly engage the next adjacent rib in the direction of travel ofsaid tool relative to said tube during said relative rotation of saidtool and tube.
 9. The method defined in claim 8, and in which a. saidtool is in operative simultaneous engagement with a plurality of saidribs whereby said slicing and raising are simultaneously accomplished ona plurality of said ribs.